The present disclosure relates to the subject matter disclosed in international application No. PCT/EP01/00783 of Jan. 25, 2001, which is incorporated herein by reference in its entirety and for all purposes.
The invention relates to a refrigerant compressor comprising a compressor housing, at least one cylinder chamber arranged in the compressor housing, a piston oscillatingly movable in the cylinder chamber, a suction chamber which is arranged upstream from the cylinder chamber and from which refrigerant enters the cylinder chamber, a pressure chamber which is arranged downstream from the cylinder chamber and into which refrigerant compressed in the cylinder chamber enters, a muffler channel which extends between a first end and a second end and via which compressed refrigerant flows from the pressure chamber into a outlet channel.
Such a refrigerant compressor is known, for example, from EP 0 926 343.
In this refrigerant compressor, refrigerant flows through the entire muffler channel in one direction, and a satisfactory attenuation is achieved, but there is a considerable space requirement owing to the length of the muffler channel through which the refrigerant flows.
The object underlying the invention is to further optimize such a refrigerant compressor with respect to the space requirement and the attenuation of pulsations.
This object is accomplished in a refrigerant compressor of the kind described at the outset, in accordance with the invention, in that the muffler channel comprises an inlet opening located between the first end and the second end.
The inventive solution makes it possible to further optimize the attenuation of pulsations in refrigerant compressors, namely by a pressure wave which enters the muffler channel propagating from the inlet opening in the direction of both the first and the second end and by the attenuation of pulsations then being even better due to reflections at both ends of the muffler channel.
Furthermore, optimum arrangement of such a muffler channel with respect to space is possible.
The outlet opening can, in principle, be arranged at very different places on the muffler channel. A particularly expedient solution makes provision for the outlet opening to be located in the area of one of the ends so that compressed refrigerant flows through the muffler channel insofar as it is conducted from the inlet opening to the outlet opening in the area of one of the ends.
In a particularly expedient solution to the realization of the muffler channel with respect to the provision of outlet openings, provision is made for the muffler channel to comprise two orifices in addition to the inlet opening, and for at least one of the orifices to form the outlet opening. This solution can be realized in a particularly simple way from a constructional point of view, in particular, also when the orifices are arranged in the area of opposite ends.
Many different possibilities of employing the inventive muffler channel are conceivable. One possibility is to so design the muffler channel that the compressed refrigerant flows into the muffler channel through the inlet opening and then in the direction of both ends to the respective outlet openings.
As an alternative or supplement to the above solution, a solution which is particularly expedient, in particular, with respect to its attenuating effect makes provision for the muffler channel extending between the ends to comprise a section through which the compressed refrigerant flows, and a section which is closed off in an acoustically blind manner, i.e., a section with reflection at the acoustically closed end. In particular, the section of the muffler channel closed off in an acoustically blind manner makes a considerable contribution towards the attenuation of pulsations or pressure waves because a reflection of a pressure wave occurs therein which then becomes superimposed with pressure waves subsequently entering the muffler channel through the inlet opening.
In particular, an acoustically blind section is designed such that an opening or a gap is created through which oil can flow off and so accumulations of oil are avoided.
Many different possibilities are conceivable for arranging the two sections relative to each other. For example, it is conceivable for the section of the muffler channel which is closed off in an acoustically blind manner to adjoin the outlet opening, so that a pressure wave entering the muffler channel first travels from the inlet opening to the outlet opening and then a portion thereof does not leave the muffler channel through the outlet opening but starting from the outlet opening propagates further in the section closed off in an acoustically blind manner.
A solution which is even more advantageous with respect to the attenuating effect makes provision for the section of the muffler channel through which the refrigerant flows and the section of the muffler channel which is closed off in an acoustically blind manner to extend away from the inlet opening, so that the pressure wave entering the muffler channel through the inlet opening is divided up into the section closed off in an acoustically blind manner and the section through which the refrigerant flows.
It is particularly expedient for the section through which the refrigerant flows and the section which is closed off in an acoustically blind manner to extend away from the inlet opening in opposite directions, so that, in particular, reflections in the section closed off in an acoustically blind manner can directly propagate further into the section through which the refrigerant flows.
So far no details have been given about the position of the inlet opening. In principle, it is conceivable to provide the inlet opening at optional places between the first end and the second end. A particularly expedient solution makes provision for the inlet opening to be located in the area of a central section of the muffler channel, preferably in the area of approximately half the entire length of the muffler channel, so that an incoming pressure wave separates into two sections which in their order of magnitude are of approximately equal length.
No details of the concrete embodiment of the muffler channel have been given in conjunction with the preceding embodiments. In an advantageous embodiment, provision is made for the muffler channel to be arranged in a part which is mountable on the compressor housing, and for the part to be mountable on the compressor housing in such a way that either the orifice arranged at the first end or the orifice arranged at the second end serves as outlet opening and leads into the outlet channel which is, for example, provided in the compressor housing.
As regards the respective other orifice, it is, for example, conceivable for it to lead into an additional section of the muffler channel extending, for example, in the compressor housing, and ending somewhere in an acoustically blind manner in the compressor housing. This would open up the possibility of additionally lengthening the muffler channel by a further section.
It is, however, particularly expedient from a constructional point of view for the respective orifice not opening into the outlet channel provided to be closed off in an acoustically blind manner.
Such an acoustically blind closure of the orifice could, for example, be brought about by a plug which is inserted or screwed in.
It is, however, particularly expedient for the orifice to be closed by an area of the part which carries the part mountable on the compressor housing.
In the simplest case, the part mountable on the compressor housing is the valve plate which is carried by a crankcase of the compressor housing and closes off the orifice with an area which covers it.
No details of the part which comprises the muffler channel and is mountable on the compressor housing have been given. This could be a separate part which is completely independent of the usual parts of the compressor housing and is inserted as a separate insert, for example, when assembling the cylinder head.
However, it is particularly expedient for the muffler channel to extend in the cylinder head and for the cylinder head to thus form the part which comprises the muffler channel and is mountable on the compressor housing.
An element forming the muffler channel, for example, a muffler pipe, can likewise be inserted in the cylinder head. It is, however, particularly advantageous for the muffler channel to be formed in the cylinder head, i.e., for example, when the cylinder head is in the form of a cast part the muffler channel is then provided in this cast part. Alternatively, it is, however, also conceivable to realize the muffler channel as a bore provided in the cylinder head.
Nor have any details of the configuration of the muffler channel in the cylinder head so far been given.
A solution which is particularly advantageous as far as the saving of space is concerned makes provision for the muffler channel to extend with one section thereof in a surface lying approximately parallel to a cylinder head cover of the cylinder head, i.e., the muffler channel which for the attenuation of pulsations with certain frequency components has preferably to have a corresponding length, can advantageously have a sufficient length by extending in this surface, without the cylinder head thereby being of considerably larger construction.
Furthermore, provision is preferably made for the muffler channel to extend with a substantial section thereof in the direction of a crankshaft and to thus preferably also extend in the direction in which the cylinders are arranged following one another in a multicylinder refrigerant compressor.
Nor have any details been given regarding the arrangement of the muffler channel relative to the pressure chamber. A particularly expedient solution makes provision for the muffler channel to extend on a side of the pressure chamber facing away from the cylinder chambers as it is, for example, thus possible to allow the muffler channel to extend along the cylinder head cover, with it being, for example, formed thereon or therein.
To obtain a suitable position for the orifices of the muffler channel, provision is preferably made for the muffler channel to have end areas extending in the direction of a crankcase so that these end areas can then be provided in a simple way with orifices which are accessible in the area of the crankcase, preferably accessible via the crankcase.
For example, the orifices of the muffler channel are located so as to face the crankcase. A particularly expedient solution makes provision for the orifices of the muffler channel to lie in a bearing surface of the cylinder head, and, thus, also sealing in the area of the orifices can be realized in a simple way, for example, by placing the cylinder head on the remaining compressor housing.
It is particularly expedient for the orifices to be sealed off in the same way as the cylinder head in the area of its bearing surface.
To achieve as good reflection and decoupling as possible at the outlet opening and the inlet opening, respectively, provision is preferably made for the inlet opening of the muffler channel to open with an abrupt cross-sectional change into the pressure chamber and for the outlet opening of the muffler channel to open with an abrupt cross-sectional change into the outlet channel.
The abrupt cross-sectional changes are preferably of such size that the abrupt cross-sectional change between the muffler channel and the outlet channel is at least by a factor 2 or 3, and, in this case, an abrupt cross-sectional change occurs from a small cross section, namely that of the outlet opening, to a large cross section, namely that of the outlet channel.
It is even better for the abrupt cross-sectional change to be at least by a factor 5.
Furthermore, the decoupling between the muffler channel and the pressure chamber is likewise promoted by the abrupt cross-sectional change between the muffler channel and the pressure chamber being by at least a factor 3, even better by a factor 5, and, in this case, an abrupt cross-sectional change occurs from the large cross section of the pressure chamber to a cross section which is smaller by the factor 3 or 5, namely that of the inlet opening of the muffler channel.
It is even better for this abrupt cross-sectional change to also be greater.
No further details of the type of the muffler channel have been given in the above explanation of the individual embodiments. It is, for example, conceivable to design the muffler channel as a channel with a constant cross section.
As an alternative or supplement thereto, it is, however, also conceivable to provide the muffler channel with cross-sectional constrictions, for example, produced by screens, in order to further increase the attenuating effect, so that the muffler channel has different cross sections at different places in the longitudinal direction thereof.
The cross-sectional constrictions and the cross-sectional expansions can be arranged in each section of the muffler channel, for example, in the section through which the refrigerant flows or in the section which is closed off in an acoustically blind manner.
It is, however, also conceivable to provide the cross-sectional constrictions and cross-sectional expansions in both of these sections.
It is particularly advantageous for the cross-sectional constrictions and cross-sectional expansions to be arranged symmetrically in relation to the inlet opening.
Further features and advantages of the invention are the subject of the following description and the appended drawings of an embodiment.